Method for synchronizing state information of a home wireless system

ABSTRACT

A method of synchronizing state information of a home wireless system wherein the home wireless system comprises a plurality of peripheral wireless nodes ( 14; 16; 19; 21; 23 ) and a first gateway ( 12 ) having wireless communication means for communicating with and controlling associated peripheral wireless nodes, the method comprising the steps installing at least one second gateway ( 26 ) in said home wireless system, assigning peripheral wireless nodes to said first gateway ( 12 ) or anyone of said at least one second gateway ( 12 ′), and each gateway directing each assigned peripheral wireless node to communicate with an assigned gateway, receiving in a first gateway system state affecting input message from an associated peripheral wireless node, determining in said first gateway a resulting system state based on said input, and communicating said resulting system state as a state change message from said first gateway to said at least one second gateway.

TECHNICAL FIELD

The invention relates to a method and a device for controlling a homewireless system. The home wireless system in general can be any type ofwireless system comprising a plurality of peripheral wireless nodes,such as an intruder alarm. Specifically it can be a security systemhaving a plurality of wireless detectors sensitive to the presence orpassage of persons and objects communicating with a gateway.

PRIOR ART

Home wireless systems in general comprise a plurality of wireless nodesthat can be connected to a communication system through a node controlunit or a control panel. An application of home wireless systems isalarm systems. Security and alarm systems used today normally comprise acontrol panel also referred to as a gateway that is connected to acentral station, either by a telephone line or by a wirelesstelecommunications system such as GSM or other radio frequency systems.The connection also can be through the internet. The gateway can beprovided with input means or be activated and controlled by controldevice such as a keypad which can be a wireless remote device.

The alarm system can be armed in different ways and into different alarmsystem states, such as “Disarmed”, “Armed Home” and “Armed Away”. If thesystem is set to “Disarmed” it will not alarm to perimeter or interiordetectors. Still, fire detectors, other gas detectors, flooding events,power break down events and similar detectors normally will be armedalso in the “Disarmed” state. If the alarm system is set to a firstarmed state referred to as “Armed Home” the alarm system will generatean alarm at the occurrence of a breach of a first group of selecteddetectors such as perimeter detectors and selected interior detectors,but not to a breach of the interior detectors in general. If the systemis set to a second armed state referred to as “Armed Away” it will alarmto a breach of the perimeter or interior detectors and normally to alltypes of detectors.

The state of the system is determined by the needs of the occupants ofthe premises. If all of the occupants are leaving the premises then thealarm system should be set to “Armed Away”. If the occupants will bestaying within the premises for an extended period of time then thealarm system can be set to “Armed Home”. This alarm setting can beappropriate for instance when the occupants are sleeping within thepremises or are staying within a defined part thereof. For otherscenarios the alarm system should be set to “Disarmed”.

In the “Armed Home” state a selected group of detectors is armed. Invarious embodiments the selected group of detectors includes theperimeter detectors and interior detectors covering sections of thepremises that are not used by the occupants. Each installation can beset up with different detectors included in the selected group.

A prior art alarm system is disclosed in U.S. Pat. No. 6,895,082 andcomprises one alarm unit in combination with a line seize module. Thealarm unit includes a transmitter/receiver, a control panel function, akey pad, an input/output port connected to a telephone line and an autodialer for normally communicating with a remote monitoring station overthe public switched telephone network.

Another alarm system including a camera device is disclosed in U.S. Pat.No. 6,570,496. In this system a premise-protecting control panelcommunicates with a sensor, providing a message in some or all cases ofsensor signals. A remote receiver receives the messages of the controlpanel. A camera device is combined with the sensor for acquiring videodata that allows further analysis into the matter of a givensensor-detected event.

US20060132303 discloses an RFID security network using system componentdiversity and system spatial diversity. The security network includes aplurality of network base units, each communicating with a plurality oftransponders, or security transmitters. Through appropriate distributiveplacement of the plurality of base units, along with appropriateplacement of the transponders, the redundancy and reliability of the RFcommunication links between one or more base units and one or moretransponders is increased.

U.S. Pat. No. 8,022,843 discloses a wireless sensor network in anaircraft. A plurality of wireless sensors is provided together with aplurality of wireless routers. Multiple routers may send data to onegateway to provide redundancy. Signals from sensors can be routedthrough different routers to reach a gateway.

Within any one security network in accordance with US20060132303, and atany one particular time, there will generally be only one base unitwhose controller function has been assigned to be the master controllerfor that security′ network. All other controller functions within otherbase units will generally be slaved to the master controller. The baseunit whose controller function is presently the master controller maysometimes be termed the master controller. The term gateway in thedocument refers to the functional capability of a base unit thatincludes a telecom interface. Each base unit can communicate with atleast one other base unit and is capable of routing. Each base unit hasa unique address.

When there are multiple controller functions installed in a singlesecurity network in accordance with US20060132303, the controllerfunctions arbitrate among themselves to determine which controllerfunction shall be the master controller for a given period of time. Thepreferred arbitration scheme consists of a periodic self-check test byeach controller function, and the present master controller may remainthe master controller as long as its own periodic self-check is okay andreported to the other controller functions in the security network. Ifthe present master controller fails its self-check test, or has simplyfailed for any reason or been disabled, and there is at least one othercontroller function whose self-check is okay, the failing mastercontroller will abdicate and the other controller function whoseself-check is okay will assume the master controller role. In theinitial case or subsequent cases where multiple controller functions(which will ideally be the usual case) are all okay after periodicself-check, then the controller functions may elect a master controllerfrom among themselves by each choosing a random number

The gateway of a home wireless system acts as a system or networkcontroller in the home or in a building. A drawback of prior art systemsis that a failure of the gateway can disable a complete installation ofa home wireless system. In alarm systems such a failure could beextremely inconvenient.

An object of the invention is to overcome the drawback of prior artsystems and to decrease substantially the vulnerability of such systems.At least one second network controller or gateway is installed in thehome wireless system and a further object of the invention is to improvethe process of binding wireless devices to an available gateway. In anapplication comprising at least two gateways there could be an integrityproblem because each gateway may indicate different states of theapplication, for instance based on information received from differentwireless nodes. It is a further object of the invention to ensure thatthe application will present a uniform definition of the present state.In various embodiments of the invention communication redundancy withinthe system is also achieved. By limiting the amount of state indicatinginformation that is exchanged between gateways it is possible tominimize RF message traffic in the application.

SUMMARY OF THE INVENTION

In accordance with the invention a method of controlling a home wirelesssystem is provided. The home wireless system comprises a plurality ofwireless nodes including a first gateway and at least one second gatewayand at least one wireless peripheral device. The home wireless systemforms an installation that can include a conventional home securitysystem that comprises at least one wireless alarm detector and at leasttwo gateways. Each wireless peripheral device repeatedly runs through alink establishment process and is then bound or associated to onegateway. No gateway of the system operates as a master unit. Instead,all gateways operate in a distributed mode.

Generally, a communication path is established between the wirelessperipheral device and the associated gateway through a linkestablishment procedure or a link setup process. The link setup processcomprises a link scan, also referred to as discover, a link request andfinally a link response. After finalizing the link setup process anycommunication to and from remote devices is controlled by the associatedgateway. In accordance with the invention each gateway is also designedto operate as a system controller in relation to any external systemsand a remote central monitoring station (RCMS). Gateways of the systemcooperate to automatically distribute system control functions. Eachgateway in a multiple gateway cooperative controls a subset of the homewireless system forming a physical installation.

Each wireless peripheral device is associated or bound to one gatewayfor communication. Each gateway instructs all bound peripheral deviceshow proceed with the wireless communication. Any messages created in aperipheral device are communicated through and acknowledged by theassociated gateway.

Each wireless peripheral device attempts to establish a link to agateway, should communicated messages sent to the bound gateway not beacknowledged as expected. After establishing a link to and thus bindingto a gateway the non-acknowledged message is sent again. In variousembodiments wireless peripheral devices or nodes automatically perform alink establishment process referred to as a login procedure when bindingto a gateway. The login procedure is used also when the wirelessperipheral device establishes a link to a gateway a first time. In thelogin procedure an identification message is broadcast by the wirelessperipheral device. The broadcast of an identification messagecorresponds to a link scan.

Each gateway receiving the identification message from a wirelessperipheral device would be able to bind the wireless peripheral deviceto itself by responding to the identification message in a predefinedway. In various embodiments each gateway that received theidentification message delays the transmission of a login or linkrequest message in accordance with a set of rules. The set of rules usedfor determining the delay can be based on different metrics, such assignal quality metric, previous ownership metric or preassigned rankmetric. These metrics are further explained below.

When the wireless peripheral device receives the login request message alink or login response signal is transmitted to complete the loginprocedure. In various embodiments the login request message includes asession encryption key that the gateway and peripheral device canutilize for secure transmission from then on for every message in eachdirection.

Each gateway is provided with a first set of communication means forcommunicating with a remote security server and with a second set ofcommunication means for communicating with peripheral devices and othergateways. At least the second set of communication means are designedfor wireless communication. Peripheral devices comprise correspondingmeans for wireless communication with the gateway.

All nodes share one radio frequency (RF) channel. However, each nodemust be able to send and receive RF messages to and from other nodeswithin its subset of the installation while ignoring messages from anyother subset. In various embodiments each gateway acts as a master withregard to an RF network comprising the gateway and at least one wirelessperipheral device. Other gateways act as masters for their respective RFnetwork.

In various embodiments the RF channel can manually or automaticallychanged in case of detecting noise, jamming or other RF transmissionproblems on the current RF channel. The peripheral devices will adapt tothe channel change by logging into the new RF channel at the nexttransmission.

Each gateway and each peripheral device it controls use specificaddresses included in messages. As a result the RF networks arepartitioned by a form of CDMA (Code Division Multiple Access). Eachgateway will only process messages from the peripheral nodes itcontrols, and it will ignore messages from peripheral nodes it does notcontrol. Likewise, each peripheral node will only process messages fromits controlling gateway.

In various embodiments the gateways used in an installation have longerrange of use than the wireless peripheral devices. Some reasons for abetter performance can be AC mains power, better RF input filtering,better antennas, and dual radio diversity. Because of this, multiplegateways may be more likely to be able to communicate with each other,in large premises, than every node is be able to communicate with everygateway. By placing gateways strategically within premises, it can beguaranteed that every peripheral node has an adequate RF communicationlink with at least one gateway. In installations where the gateways canall communicate with each other, further improved system performancewill be provided.

In various embodiments a gateway receiving messages intended forgateways of other installations processes such messages for creatingmetrics and for monitoring also other installations or systems. Anyprocessed metrics can be used for finding network problems or differentkinds of sabotage conditions. The RF communication link between gatewaysalso can be utilized for supervising the network. This could be used fordetecting problems caused by RF noise, or intentional sabotage. If agateway detects or suspects an RF trouble-condition, it can temporaryincrease the frequency of a supervision cycle on other gateways, toquicker detect and act upon RF trouble.

In an installation all wireless peripheral devices must be distributedautomatically among a pool of gateways. Furthermore, if a gateway fails,its peripheral nodes must be redistributed among the pool of survivinggateways. In various embodiments an RF protocol login procedure can beused. When a wireless peripheral device starts up it begins broadcastingan identification message. Every gateway that receives theidentification message will try to respond with a login request message.By imposing rules or metrics in the RF protocol login procedure it ispossible to proceed further with one gateway only by delaying thegateway login request message.

One metric can be based on link quality. This metric can comprise radiosignal quality based on RF signal strength (RSSI), Link QualityIndicator (LQI) that measures the error in the incoming modulation ofsuccessfully received packets (packets that pass the CRC criterion) andother similar properties. The better signal quality for theidentification message received in a gateway the shorter the delay.Thus, gateways “closer” (better RF link quality) are favoured andgateways “farther” (worse RF link quality) are disfavoured for capturinga particular peripheral node.

Another metric can be based on previous link status in combination withhistory ownership. If a previous communication link between a gatewayand a wireless node had a high quality level a shorter delay isselected. If a gateway has previously owned a peripheral node, theshorter the delay. This results in a more stable network topology; aperipheral node normally will not alternate between two gateways withequal signal quality metrics.

A further metric can be based on preassigned rank. A particular gatewaycan be favoured and be instructed to use a shorter delay. In this waymore wireless peripheral devices will be bound to this gateway.Different metrics can be combined.

In various embodiments a fail-over procedure is automatically initiatedif a gateway fails. In such a case its peripheral nodes areautomatically and transparently transferred to another surviving oroperative gateway. In a single gateway installation, a peripheral nodethat has an event (such as an alarm) to report, will attempt to send anRF message to the bound or associated gateway. If the gateway fails toacknowledge the message, the peripheral node will retry a few times andthen begin the login procedure again by broadcasting the identificationmessage.

From a peripheral node's perspective, fail-over in a multiple gatewaycooperative is no different from a situation where the link is lost to asingle gateway. If a gateway fails, the next time a peripheral node itowned attempts to transmit a message, it will fail and begin the loginprocedure again by broadcasting the identification message. This time,however, another operative gateway will send a login request messagefirst and capture the peripheral node. After the peripheral node hascompleted the login procedure, it will transmit again the original eventmessage to its new RF master gateway. Thus, fail-over from a failedgateway to a surviving gateway has occurred automatically andtransparently.

A new link establishment process will also take place if thecommunication link between a gateway and a wireless node is broken. Thismay happen when radio signals are blocked or disturbed by objects orinterference from other radio signal sources.

An application always is placed in a state, such as an arming state(described above), an alarm state, peripheral device low battery stateand other dynamic and intermediate states. All gateways in anapplication need to synchronize the present state, so as to ensure thatthe application or the system represents a unitary state. Each gatewayin a multiple gateway application may receive new information from awireless peripheral device that can influence the application systemstatus. After receiving such information the gateway determines whetherthe new information has such an impact that a resulting system statusneeds to be communicated to other gateways of the application. If thisis the case the receiving gateway communicates the resulting systemstatus to other gateways of the application.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above recited and other advantagesand objects of the invention are obtained will be readily understood, amore particular description of the invention briefly described abovewill be rendered by reference to specific embodiments thereof which areillustrated in the appended drawings.

Understanding that these drawings depict only typical embodiments of theinvention and are not therefore to be considered to be limiting of itsscope, the invention will be described and explained with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1 is a schematic view of an installation of a home wireless systemcontrolled in accordance with one embodiment of the invention,

FIG. 2 is a schematic block diagram showing an embodiment of aninstallation in accordance with the invention,

FIG. 3 is a schematic flow chart of a general link establishment processof a wireless peripheral device used in accordance with the invention,

FIG. 4 is a schematic flow chart showing a process of a wirelessperipheral device in a home wireless system in accordance with theinvention including a link establishment process, and

FIG. 5 is a schematic flow chart showing a process in a networkcontroller in a home wireless system in accordance with the inventionincluding a link establishment process.

DETAILED DESCRIPTION

In the embodiment shown in FIG. 1 an installation comprising a homewireless system is installed in a building 10. The home wireless systemis an alarm system installation and comprises a plurality of wirelessperipheral nodes including wireless peripheral devices, a first gateway12 and a second gateway 12′. One wireless peripheral node is a firstinfrared detector 14 mounted in the corner of a room close to theceiling. The first infrared detector 14 has a sensing area that coversthe first gateway 12. A first perimeter alarm detector 16 is mounted ata window 17 in the same room. The infrared detector operates in aconventional manner to detect presence and movements of objects emittinginfrared radiation. The perimeter alarm detector also operates in aconventional manner to detect when a door or a window is opened. Invarious embodiments the perimeter alarm detector comprises a magneticsensor that will detect when a magnet attached to the door or window ismoved.

A second gateway 12′ is arranged in a second room separated from theroom where the first gateway 12 is arranged. A second infrared detector14′ is mounted in the same room as the second gateway 12′ to cover itwithin its operative area and a second perimeter alarm detector 16′ ismounted at a window 17′ in the same room. A keypad 19 is mounted closeto a front door 20 of the building 10. The keypad 19 is used by anoperator of the alarm system to arm and to disarm the alarm system. Alsothe keypad 19 is a wireless peripheral node. The front door 20 iscovered by a third perimeter alarm detector 21. Another type of wirelessperipheral device is a smoke detector 23 mounted in the ceiling ofbuilding. In various embodiments a plurality of smoke detectors 23 arearranged throughout the building 10 to ensure that fire can be detectedat an early stage.

Depending on different circumstances the first gateway 12 and the secondgateway 12′ are connected to a remote central monitoring station 22either through a wired connection 24 or through a wireless connection.The connection to the remote central monitoring station 22 can also bethrough the internet 26. The wired connection 24 can be part of a publicswitched telephone network 25. In various embodiments the remote centralmonitoring station 22 comprises an interface module 27, a database 28and a web server 29. The database 28 stores installation and applicationdata relating to the installation including all wireless network nodesand alarm settings.

During initial installation of a prior art system each peripheral nodeattaches to the single gateway in accordance with a specific loginprocedure. The peripheral node broadcasts an RF signal comprising anidentification message including a unique identification number referredto as the node ID. The single gateway receives the broadcastidentification message and examines the node ID. If that node ID is partof the gateway's installation, it responds to the identification messagewith the transmission of a login request message specifically addressedto the peripheral node that broadcast the identification message. Invarious embodiments installation and application data including the nodeID of all peripheral nodes included in an installation are stored in theremote central monitoring station 22 and are transferred to the gateway.A home wireless system installation can comprise a plurality ofdifferent applications, such as alarm, monitoring, measuring and otherservices.

In various embodiments the login request message includes a temporarysession encryption key that is used by the gateway and the peripheralnode for communicating in both directions. After receiving the loginrequest message the peripheral node responds with the transmission of alogin response message specifically addressed to the gateway to completethe login procedure. All RF messages sent from a wireless peripheraldevice are acknowledged by the gateway that receives and processes themessage in an acknowledgement procedure.

In an installation in accordance with the invention as shown in FIG. 1 afirst gateway 12 and a second gateway 12′ are included in theinstallation. Both gateways are connected to the remote centralmonitoring station 22 and have received information regarding theinstallation. The remote central monitoring station 22 also comprisesconventional means for receiving alarm signals from gateways of aninstallation. The installation procedure of the installation shown inFIG. 1 starts with the same sequence that is described above. A wirelessperipheral device, such as the first infrared detector 14, broadcasts anidentification message that could be received by the first gateway 12and the second gateway 12′.

In accordance with the invention only one gateway binds the broadcastingwireless peripheral device to itself. In various embodiments a gatewaythat receives an identification message delays the transmission of thelogin request message. The delay is based some metrics. In oneembodiment of the invention the metrics is a signal quality metric. Agateway receiving the identification message measures or determines thesignal quality of the received signal. The better the signal quality ofthe identification message received by the gateway the shorter thedelay.

As a result a gateway arranged in such a relation to the peripheraldevice that a better signal quality is achieved is favored before otherpresent gateways. The favored gateway will be the first to send a loginrequest message and consequently will bind the peripheral device toitself. Other gateways of the installation also may transmit loginrequest messages but these will not be processed and accepted by theperipheral device because it then is already bound to the first gateway.

Another metric can be based on previous ownership or previous linkstatus. If a peripheral node previously has been bound to a specificgateway with good communication link quality a shorter delay can be usedby the gateway. This results in a more stable network topology; aperipheral node will not alternate between two gateways with equalsignal quality metrics.

A further metric can be based on preassigned rank. In some installationsit would be preferred to bind a specific gateway to a specificperipheral device. In such cases the delay in the gateway can shortened.The different metrics can be combined in an installation.

The described login procedure also provides redundancy and an automaticfail-over function. Should a gateway bound to one or a plurality ofwireless peripheral devices fail all bound wireless peripheral devicesautomatically and transparently will be transferred to another gateway.In various embodiments the acknowledgement procedure is used to ensurethis function. If no acknowledgement message is received in a wirelessperipheral device after transmitting a message, the wireless peripheraldevice will retry a few times within a comparatively short time period.The message sent by the wireless peripheral device could be an alarmmessage, a periodic status message or another type of message. Aperiodic status message is broadcast by all peripheral devices at someintervals.

In the embodiment shown in FIG. 1 the first infrared detector 14 whichis bound to the first gateway 12 detects movement of an object in thedetection area (marked). An alarm signal message is transmitted andshould be received and processed by the first gateway 12, which isassociated with and previously has been bound to the first infrareddetector 14. However, for some reason the first gateway is not able totransmit an acknowledge signal or for some reason the acknowledge signalis blocked or disturbed. After a few attempts of sending the messageagain the first infrared detector will begin the login procedure againby broadcasting the identification message.

Since the identification message is broadcast all gateways in theinstallation receive the identification message. If the previouslyassociated gateway, that is the first gateway 12, does not respond thesecond gateway 12′ will respond with a login request message including atemporary session encryption key. The first infrared detector 14 thenwill bind to the second gateway 12′ by sending a login response signalusing the temporary session encryption key received from the secondgateway 12′. Following the login procedure the original alarm signalmessage is again transmitted also with use of the temporary sessionencryption key received from the second gateway 12′. After receiving theoriginal alarm signal the second gateway 12′ then can send an alarmmessage to the remote central monitoring station 22 in accordance withnormal routines.

Where the first gateway 12 as well as the second gateway 12′ receive andprocess the identification message broadcast by the first infrareddetector 14 a metric as set out above will be utilized. As a resulteither the first gateway 12 or the second gateway 12′ will transmit thelogin request message. Using the metric based on signal quality orsignal strength the first gateway 12 will be applying a shorter delayand be the first gateway to respond. Also using the metric based onprevious ownership or previous link status will result in the firstgateway 12 responding first and thereby binding the first infrareddetector 14. The third metric based on a predefined setup or assignmentmay lead to another result, should the second gateway 12′ be a higherranked unit.

A situation similar to a failure situation involves a gateway restart.Since the session encryption keys between the gateway and its peripheralnodes are temporary, all nodes will be marked logged out when thegateway restarts. However, a peripheral node does not know it has beenlogged out until it attempts to send the next RF message (perhaps analarm message, perhaps only periodic status). That message transmissionand its retries, using the previous temporary session encryption key,will fail, and the peripheral node will begin the login procedure againby broadcasting the identification message. After it has completedlogin, will transmit the original event message again using the newtemporary session encryption key.

In the embodiment shown in FIG. 1 a small storeroom 34 is arranged as anannex connecting to the building 10. A third perimeter alarm detector 36is arranged at a storeroom door 38. Due to fact that several wallsseparate the third perimeter alarm detector 36 and the first gateway 12radio frequency signals that are transmitted from the third perimeteralarm detector 36 do not reach the first gateway 12 in a satisfying way.The range of the third perimeter alarm detector 36 is indicated at line37. The shorter distance and fewer walls in respect of the secondgateway 12′ allows it to properly receive the radio signals transmittedby the third perimeter alarm detector 36.

During a login procedure initiated by the third perimeter alarm detector36 no login response message is transmitted from the first gateway 12because it does not receive signals having appropriate signal qualities.In various embodiments the gateways in an installation are provided withmore powerful radio transmitting means than the wireless peripheraldevices. This could be because the gateways comprise higher capacitypower supplies or are connected to a power line. The second gateway 12′receives a radio signal that complies with presently applied standardsand sends a login response message in accordance with the proceduredescribed above.

The first gateway 12 still can be capable of communicating with thesecond gateway 12′ as a result of the more powerful radio transmittingmeans and may communicate information about the third perimeter alarmdetector 36. By placing gateways strategically within a building it ispossible to guarantee that every peripheral node has an adequate RF linkwith at least one gateway. As long as the gateways can all communicatewith each other, the installation will function properly. To achievefull redundancy the installation should include enough gateways forevery peripheral node to be able to communicate with at least twogateways.

An installation such as the alarm system shown in FIG. 1 holds a largeamount of dynamic state information, such as arm state, alarm status,peripheral battery status, etc. in a total system state informationdataset. Similar information is stored also in other types of homewireless systems. Each gateway or controller continuously receivesinputs from different authenticated sources such as peripheral nodes, aRCMS, adjacent systems, etc. that affects a distributed state of theapplication or system.

An alarm system with distributed gateways operating as systemcontrollers should synchronize state among the controllers. However, invarious embodiments only a small subset of the total system stateinformation dataset needs to be strictly synchronized for successfuloperation. Preferably, only higher level, abstract system state changes,such as entry alarm, arming state, and smoke detected, are distributedand synchronized. Upon receiving state change information the receivinggateway determines whether the received information relates such a highlevel system state change. If this is the case a resulting applicationstate is distributed among other gateways of the application. In variousembodiments also time stamp data relating to the actual time of thestate change is included in a distributed message together with theresulting application state.

Other information or data items, especially those pertaining toperipheral nodes and/or low level events, need not to be distributedbecause they do not jeopardize important functions of the system. Theycan also be recreated as necessary. Also, the contact status of aperipheral device to an associated gateway needs to be monitored by theassociated gate only, not by other gateways. In the case of a gatewayfailure all peripheral devices associated to the failing gateway willestablish contact with another gateway.

In various embodiments a message digest of the resulting applicationstate is included when a gateway has determined that receivedinformation has changed the state and the resulting state needs to bedistributed among the gateways of the installation. It is possible alsoto include a message digest of the state prior to the state change.Different techniques, such as MD5 or SHA256 and other hash algorithmsexist for calculating or determining a message digest. The messagedigest of an application state is a transformation of status data ofsystem components and will improve application integrity considerations.

In case of conflicting application state information differentarbitration methods can be used. A simple arbitration method is tocompare the age of the applications state changes and to set thegateways to select the latest or newest state change. In variousembodiments a source rank for the state change is used for arbitration.Normally, the highest rank state change is selected. The source rank canbe based on a combination of the time of state change, source of statechange, uptime of the receiving gateway and number of source links.

Many data items, especially those pertaining to peripheral nodes, can berecreated as necessary. In accordance with various embodiments of theinvention only higher level, abstract system state changes (e.g. entryalarm) rather than low level events (e.g. a specific smoke detectorreporting low battery status) are synchronized. As a further example,only the gateway a peripheral node is attached to really needs to trackthe peripheral's contact status. If that gateway fails, and the nodelogs into another gateway, after completing login the peripheral nodewill send the new gateway a contact state message containing theviolation state of all the node's detector contacts. This schememinimizes the amount of information that needs to be synchronizedbetween gateways in the cooperative, and minimizes also the resulting RFmessage traffic.

In various embodiments a second gateway can utilize the RF communicationlink of another gateway for tunnelling messages to a remote centralmonitoring station (RCMS). For example if the second gateway up-link toRCMS is very slow or unreachable, or has a higher cost, another gatewayup-link can be utilized.

A home wireless system has a large amount of persistent systemconfiguration information. An alarm system holds information such asalarm detector definitions, user PIN codes, etc. This configuration,which is stored in the central monitoring station and is pushed to eachgateway from the central monitoring station, should be identical amongthe gateways in a multi-gateway installation or the system may behaveerratically. For example, if a perimeter alarm detector has been addedto the system, and the perimeter alarm detector configuration has beenpushed to one gateway but not to another, the new perimeter alarmdetector may or may not function correctly. It is therefore important toguarantee that configuration is consistent among all the gateways in amulti-gateway installation.

In various embodiments the remote central monitoring station generates astrictly increasing configuration revision number every time theinstallation's gateway configuration (which is shared by all gateways inthe multi-gateway installation) changes. This configuration revisionnumber is pushed to each gateway along with whatever configuration datahas changed.

Each gateway includes its configuration revision number in a periodicstatus messages that it sends to other gateways in the multi-gatewayinstallation. When each gateway receives periodic status from anothergateway, it compares its configuration revision number to that in theperiodic status message. If the other gateway's configuration revisionnumber is greater, indicating newer configuration, the receiving gatewaywill send a special report message to the central monitoring station andrequest a configuration update. In this way, when new configuration isreceived in one gateway in the multi-gateway, the changes will quicklypropagate to all other gateways. Normally, it is not possible for thecentral monitoring station to push new configuration to all the gatewaysin an installation directly, because a gateway is protected behind anetwork firewall or a similar protection scheme. In such installationsthe central monitoring station has to wait until the gateway opens acommunication session and sends out a report, through the firewall, tothe central monitoring station. When the communication session is openedinformation can be transferred from the central monitoring station tothe gateway.

In various embodiments an update of state or configuration could bedetected by arranging the first gateway to calculate a checksum of allstates and configuration. This checksum can then be monitored by anyother gateway. If the checksum changes, the other gateway determinesthat the state or configuration is changed. Such a change can be used bythe second gateway to start an update as well.

The schematic view in FIG. 2 shows a basic installation with one remotecentral monitoring station 22, a first gateway 12, a second gateway 12′and a third gateway 32. A plurality of wireless peripheral devices isalso included in the installation. The remote central monitoring station22 normally is connected to and handles a plurality of installations. Adatabase 28 stores separately data relating to each installation. Suchdata can include installation configuration and user or owner data. Aninterface module 27 allows users to interact with the database and tochange some settings of the installation. I various embodiments theinterface module 27 is arranged to exchange data through the internet. Acontrol and communications unit 31 controls the function of the remotecentral monitoring station and the communication with all associatedgateways.

Each gateway comprises first communication means 40 for communicationwith radio frequency signals and second communication means 42 forcommunication with remote units such as the remote central monitoringstation 22. The second means for communication is capable ofcommunicating over the internet and/or over telephone lines. In variousembodiments the second means for communication comprises cellulartelephone module for communication by GSM, GPRS and similartelecommunication standards. Each gateway further comprises a centralunit 44 with memory means and timing means. Said timing meanscontinuously keeps track of the time of events handled by orcommunicated to the gateway.

The central unit 44 maintains in the memory means data relating to theinstallation and communication settings such as temporary encryptionkeys used during communication with associated wireless peripheraldevices. The first communication means 40 is used also for communicatingwith other gateways present in the installation. A power unit 43provides the power used by the gateway. In various embodiments the powerunit 43 is connected to the mains of the premises.

Said first communication means 40 is arranged to receive and to detectthe signal strength and the signal quality of radio signals. When agateway 12 receives a radio signal comprising the identification messagefrom a peripheral device the quality and strength of the signal isdetermined in said first communication means 40. A result of thedetermination is transferred to the central unit 44 where furtheranalysis is performed based on which metric is used in the presentsystem.

The memory means of the central unit 44 of the gateways also stores datarelating to all bound wireless peripheral devices. In variousembodiments the memory means of the central unit 44 of the gateways alsostores data received from the remote central monitoring station relatingto previously bound wireless peripheral devices and various ranks ofdifferent wireless peripheral devices. These data can be used during alink establishment process as described above when other metrics areused.

Each wireless peripheral device basically comprises a wirelesscommunication unit 46 used for all communication with a gateway, asensor unit 48, a processing unit 49 and a power supply unit 50.Different wireless peripheral devices comprise different types of sensorunits 48, such as infrared sensor, magnetic sensor, smoke detector,temperature detector. In various embodiments an image capturing device52 such as a video camera or digital camera is also included in thewireless peripheral device. In the embodiment shown in FIG. 2 the imagecapturing device 52 is arranged in an infrared detector 14.

The link establishment process of a wireless peripheral device into thehome wireless system is shown in FIG. 3. In various embodimentsinstallation information comprising identification data, setup data andapplication data of each wireless peripheral device and data definingthe type of wireless device is maintained in the remote alarm receivingcentre 18. The installation information also is transferred to each oneof the gateways of the installation. As shown in FIG. 3 a bindingwireless peripheral device first is activated in block 54 and theninitiates the link establishment process by broadcasting anidentification message in block 56. The identification message includesan address of the wireless peripheral device.

The identification message is broadcast as a radio frequency signal (RF)and will be received by all gateways receiving a sufficiently strongradio signal. In accordance with the invention all gateways receivingthe signal will apply a scheme before transmitting a reply message asset out above. The scheme will ensure that a reply message will be sentfirst from one responding gateway as a login request message as depictedin block 58. The login request message is directed specifically to thebinding wireless peripheral device by including in the login requestmessage the address of the binding wireless peripheral device. The loginrequest message includes also an address of the responding gateway. Ifno login request message is received in the binding wireless peripheraldevice the process will continue in block 56 by broadcasting theidentification message again.

In various embodiments a temporary session encryption key is generatedin the responding gateway. The temporary session encryption key isincluded in the login request message. The responding gateway and thebinding peripheral node will use the temporary session encryption keyfrom then on for every message in each direction. Each message will alsobe directed to a specific receiving gateway or wireless peripheraldevice by including in the message the appropriate address.

As soon as a login request message is received in the binding wirelessperipheral device it will transmit a login confirmation message asdepicted in block 60. The login confirmation message is directedspecifically to the responding gateway by the inclusion of appropriateaddress. As a result the link establishment process is completed, thewireless peripheral device is bound to one gateway and a communicationpath is established.

An operational process of a home wireless system in accordance with theinvention shown in FIG. 4 includes a link establishment process asdescribed above with reference to FIG. 3. When a login confirmationmessage is transmitted in the wireless peripheral device it will enteran operation mode as depicted in block 62. In an alarm installation itcan correspond to an enabled mode where a sensor in the wirelessperipheral device is enabled. Any event triggering a sensing unit of thewireless peripheral device, or presence of a previously occurred event(see below), will result the transmission of an alarm message asdepicted in block 64. The message can also be an event message informingthe gateway about low battery or other status information of the boundwireless peripheral device.

After transmitting the alarm or event message the wireless peripheraldevice checks in block 64 if an acknowledgement message is received fromthe bound gateway. During normal conditions an acknowledgement messageis received and the wireless peripheral device returns to the operationmode in block 62. The alarm event or any other message is handled by thebound gateway in a conventional manner.

Should an acknowledgement message not be received, for instance becausethe bound gateway is malfunctioning or radio transmission is disturbed,a fail-over process is initiated and a check is made in block 68 if apredetermined number of retries of transmitting the event messages hasbeen reached. If this is not the case the process returns to block 64and the event messages is again transmitted. If a predetermined numberof retries has been made it is concluded that the bound gateway is morepermanently out of order, or that no contact can be established. Theprocess returns to block 56 and a new login process is initiated. Whenreaching block 62 a previously occurred and unacknowledged event signalstill will be present. As a result the process will continue in block 64by transmitting the unacknowledged event signal.

In various embodiments a common situation occurs when a gateway isrestarted. After a restart of a gateway all wireless peripheral devicesincluded in the installation are considered logged out from the gateway.As a result any messages received from a wireless peripheral deviceafter restart will not be processed and will not be acknowledged by thegateway. As soon as an identification message is received from awireless peripheral device the login process starts in the gateway asset out above by the transmission of a login confirmation message.

One embodiment of a process of starting or restarting a networkcontroller or a gateway 12 is shown in FIG. 5. In block 68 the gatewayis activated. A contact then is established between a remote centralmonitoring station (RCMS) and the gateway. The gateway receives in block70 a set of installation and application data from the RCMS includingthe preferred metrics to be used during a link establishment process.The data also can include information relating to previously boundwireless peripheral devices.

After receiving installation and application data from the RCMS thegateway 12 is prepared in block 72 to receive an ID message fromwireless peripheral devices of the installation searching for a gateway.When an ID message has been received the central unit 44 the gateway 12determines in block 74 response criteria based on data received from theRCMS. At least one of the metrics as set out above is utilized forcalculating a delay. In various embodiments different criteria andmetrics are combined and weighted. Signal strength and signal quality,previous relationship with wireless peripheral device, that is whetherthe wireless peripheral device recently or ever was bound to thegateway, and other criteria can be used.

Based on the selected metrics and detected signal strength and or signalquality a login request message is transmitted in block 76. In variousembodiments a delay is calculated on the bases of the selected metricsand detected signal strength and or signal quality and the login requestmessage is transmitted after said delay. The wireless peripheral devicethat transmitted the ID message will receive the login request messageand reply with a login confirmation message that is received in thegateway in block 78. After receiving the login confirmation message thegateway or network controller is in operation mode as shown in block 80.

While certain illustrative embodiments of the invention have beendescribed in particularity, it will be understood that various othermodifications will be readily apparent to those skilled in the artwithout departing from the scope and spirit of the invention.Accordingly, it is not intended that the scope of the claims appendedhereto be limited to the description set forth herein but rather thatthe claims be construed as encompassing all equivalents of the presentinvention which are apparent to those skilled in the art to which theinvention pertains.

1-7. (canceled)
 8. A method of synchronizing state information of a homewireless system wherein the home wireless system comprises a pluralityof peripheral wireless nodes and a first gateway having wirelesscommunication means for communicating with and controlling associatedperipheral wireless nodes, the method comprising the steps: a)installing at least one second gateway in said home wireless system, b)assigning peripheral wireless nodes to said first gateway or anyone ofsaid at least one second gateway, and each gateway directing eachassigned peripheral wireless node to communicate with an assignedgateway, c) receiving in a first gateway system state affecting inputmessage from an associated peripheral wireless node, d) determining insaid first gateway a resulting system state based on said input, and e)communicating said resulting system state as a state change message fromsaid first gateway to said at least one second gateway.
 9. A method asclaimed in claim 8, also comprising communicating resulting system stateonly if said system affecting input is included in a first set ofpredefined input messages.
 10. A method as claimed in claim 9, whereinsaid first set of predefined input messages include entry alarms andarming state.
 11. A method as claimed in claim 9, also comprisingincluding a time stamp associated to the actual time of system statechange.
 12. A method as claimed in claim 8, also comprising including insaid state change a message digest of the resulting state.
 13. A methodas claimed in claim 9, also comprising including in said state change amessage digest of the resulting state.
 14. A method as claimed in claim8, also comprising marking said state change message with a time stamprepresentative of said resulting system state change.
 15. A method asclaimed in claim 9, also comprising marking said state change messagewith a time stamp representative of said resulting system state change.16. A method as claimed in claim 15, also comprising selecting theresulting system state change having the newest time stamp as validwhere conflicting application state information is detected in agateway.